The present invention relates to a semiconductor device, and more particularly, to an output circuit for adjusting a slew rate of data outputted from the semiconductor device, when an operation frequency of the semiconductor device is changed.
In general, a semiconductor device includes the output circuit to output a data, and the output circuit includes a pre-driver and an output driver. The pre-driver outputs a pull-up signal and a pull-down signal which correspond to the data outputted from memory cells. The output driver outputs the data to an output pad in response to the pull-up signal and the pull-down signal.
The data transferred from the output circuit to the output pad has the slew rate, which is a change amount of output voltage per unit time. The slew rate of data is changed according to a design of a semiconductor device such as the number of the output pads. For example, when the number of the output circuits satisfies the conditions for ×4, ×8 and ×16 operation modes of the semiconductor device, the slew rate of data is depending on operation modes, that is, operation modes have different slew rate of data. Particularly, when the semiconductor device is operated in ×16 operation mode, the slew rate of data is lower then that of ×4 or ×8 operation mode.
FIG. 1 is a timing diagram illustrating the operation of a conventional output circuit.
Referring to FIG. 1, the slew rate of data in ×4, ×8 and ×16 operation modes are different. Generally, the output circuit is designed based on the slew rate of data corresponding to ×16 operation mode. Thus, when the semiconductor device is operated in ×4 or ×8 operation mode, the semiconductor device may consume an operation current excessively.